1. Field of the Invention
This invention relates to a thermoplastic, segmented, linear copolyesterether elastomer which has soft segments derived from a glycol of a poly(tetramethylene oxide) or a copolymer of tetrahydrofuran and 3-methyl-tetrahydrofuran. More particularly, the invention concerns such an elastomer in which the hard segments are particular cycloaliphatic groups.
2. Description of the Prior Art
Various thermoplastic, segmented, linear copolyetherester elastomers have been suggested for the production of molded articles, films and fibers. Generally, such elastomers are composed of long chain ether-ester units which constitute "soft segments" of the elastomer and short chain ester units which constitute "hard segments". For use in fibers or films, at least 70% of the polyetherester elastomer chain is soft segments.
Polyetherester elastomers in which residues of cycloaliphatic acids, esters or diols are incorporated into the polymer chain are known, as for example, from Davis et al, U.S. Pat. No. 4,349,469; Bell et al, U.S. Pat. No. 3,261,812, 3,157,619 and 3,243,413; Kibler et al, U.S. Pat. No. 3,238,178; and Kaplan, U.S. Pat. No. Reissue 32,770.
The above-mentioned patents disclose the use of cyclohexane dimethanol in the manufacture of elastomer intended for conversion into fiber or film. However, fibers or films made from such elastomers usually have certain undesirable characteristics, such as high permanent set, low tensile properties and high initial modulus. An object of this invention is to provide a thermoplastic linear polyetherester elastomer that can be converted into fibers or films in which these undesirable characteristics are significantly lessened.